1. Field of the Invention
The present invention relates to a molding method suitable for molding optical element, lens or the like.
2. Related Background Art
In the prior art, a process for injection molding by heating the mold by high frequency heating has been proposed as described in Japanese Laid-Open Patent Application No. 50-45039. The process comprises using a device having oscillation electrodes and cooling water pathway in a mold and having an external oscillator and cooling pump, heating the mold momentarily during filling of resin by means of the oscillating electrodes provided in the mold, and after completion of filling, stopping oscillation, flowing cooling water through the mold by the cooling water pump to cool and solidifying the resin.
Also, Japanese Patent Publications No. 58-40504 and U.S. Pat. No. 4,340,551 propose an injection molding process, which performs injection molding of a thermoplastic resin by prior heating of the mold surface on which the injection molded product surface is to be formed by means of high frequency induction heating before to a temperature not lower than the heating deformation temperature of the thermoplastic resin.